Method AlreadyHaveTx

src/node/txdownloadman_impl.cpp:125–147

}

bool TxDownloadManagerImpl::AlreadyHaveTx(const GenTxid& gtxid, bool include_reconsiderable)
{
    const uint256& hash = gtxid.ToUint256();

    // Never query by txid: it is possible that the transaction in the orphanage has the same
    // txid but a different witness, which would give us a false positive result. If we decided
    // not to request the transaction based on this result, an attacker could prevent us from
    // downloading a transaction by intentionally creating a malleated version of it.  While
    // only one (or none!) of these transactions can ultimately be confirmed, we have no way of
    // discerning which one that is, so the orphanage can store multiple transactions with the
    // same txid.
    //
    // While we won't query by txid, we can try to "guess" what the wtxid is based on the txid.
    // A non-segwit transaction's txid == wtxid. Query this txhash "casted" to a wtxid. This will
    // help us find non-segwit transactions, saving bandwidth, and should have no false positives.
    if (m_orphanage->HaveTx(Wtxid::FromUint256(hash))) return true;

    if (include_reconsiderable && RecentRejectsReconsiderableFilter().contains(hash)) return true;

    if (RecentConfirmedTransactionsFilter().contains(hash)) return true;

    return RecentRejectsFilter().contains(hash) || std::visit([&](const auto& id) { return m_opts.m_mempool.exists(id); }, gtxid);
}

void TxDownloadManagerImpl::ConnectedPeer(NodeId nodeid, const TxDownloadConnectionInfo& info)
{